Drying out - proceedure / is it necessary

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mjf

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Since returning to the Uk I have been in the habit of hauling my boat annually for a wash off, rub down and re antifoul. The stern gear is buffed and anodes changed.

The boat is out for 24hrs and is re-slipped. Therefore 364day in the water. A lot of peeps say that you should leave it on the hard of at least a week to 'dry out'. What needs to dry out on modern hulls please?

Previously I used to haul out every two years ( boat moored in fast current in tropical waters) and do the hull and service stern drives etc in 10days or so. This was an older boat (1990) and there was never anything remotely like damp on the hull after a couple of hours in the dry.

What is the view on the annual haul out please?
 
in/out debate

ah right, that time of year.

Yep, bit pointless hauling out modern plastic boats cos they'll get wet again when you puttem back in.

HOWEVER - the microclimate is defintiely different when in the water that when out of the water, even when ashore is near (but not on) water - you are close to the wet stuff, nicely buried in morning mist day after day during winter. I think that this makes far more of a difference that the floating thing, specially in a locked marina - but the major effects arer of course minimised with keeping windows shut, blanked with cardboard (NOT curtains, they may get mildew) taking as much stuff home to central heated house, storing other linen stuff high up in cupboards, and having a fan blow thru a dehum. This feels a bit "stuffy" but is great atmosphere for non-living things to stay dry and in better condition. Other alternative with no dehum is to leave windows open a crack, altho this hoeeps for more air movement than actually happens and every single person i have ever met who recommends this has a somewhat knackered ole boat anyway...
 
Re: What about the bits that are normally wet.

Nah, all that osmosis, thing of the past mate, ole poxy boats might get that but not the luverly new ones with gelcoat and modern technology comprising erm, a load of people with plentiful epoxy, glass fibre matting and a miniroller each...
 
Re: What about the bits that are normally wet.

Ok, thats what i thought too!

Another issue is hull stress - the boat is better supported in the actual oggin rather than sitting on a couple of wooden blocks with pit props stopping it from falling over is'nt it?

Boat looks a bit daft in a field or car park...........
 
They don\'t make \'em like they used to

I may have been fed a load of old tosh, but when I had a survey done on my boat, I asked the guy about osmosis and modern grp boats. His response was that most manufacturers now used isopthalic (sp?) resins and that these were far less susceptible to water ingress, and hence osmosis, than their predecessors.

"So", I asked, "will it prevent the boat getting osmosis"? "Oo-er, dunno, but probably not and, anyway, not for years and years and, um, er..............."

But on balance, I think it's probably true that you can keep 'em in nowadays. Lots of modern commercial grp craft (pilots, patrol boats etc.) are in the water all year and don't seem to come to grief. Think I'm right in saying that things like grp minesweepers don't even have a gelcoat, because they don't need to pay much attention to aesthetics?
 
Re: They don\'t make \'em like they used to

From what I understand, epoxy is waterproof, but gelcoat is not completely. It does get 'wet', which can let water through to the matting, which is where it reacts with any badly mixed GRP glop, which gives off gas, which causes blisters.

So in the past, when they mixed the glop by hand, it was a bit hit and miss, but now it should be much less likely, hence osmosis being relatively unlikely. If in doubt. however, haul it out. The moisture readings will definitely go down as the boat dries out on the hard, although whether it's really necssary or not, I don't know...
 
myth number 2

Nah, a bigger stress is surely during the liftout, and bigger again are the forces when the boat kerumphs along through waves. If it survives that lot then sitting quietly ashore or at sea is no prob, provided properly supported at strong points (they shd tap hull with a hammer to find solid bits) on lots of piles of wood.
 
Its the gelcoat that\'s the problem

Osmosis is caused by the different osmotic pressures set up in between the outside of the hull resting in salt water and the inside where damp resides without salt. This causes very small amounts of water to be drawn through and trapped in the gelcoat layer, which then causes blisters. OK - more modern boats may claim to have this problem boxed off due to better technology, materials and manufacturing. But I doubt it long term...

Make no mistake, gelcoat is not necessary on boats and minesweepers are indeed made of grp minus the gelcoat, in order that they may stay in service year in, year out. And these boats never suffer from osmosis. Gelcoat serves one purpose - and that's to make your boat look nice. The RN don't really care about aesthetics.

Doing maintenance ashore is a whole load easier than when afloat, so it makes sense to haul out now and again. I do mine every two years. In the interval year it gets stuck on a trailer, serviced, tarted up and dunked back in.
 
Just had an email from a friend in the know, who says:

"Basically the conversations that are going around are correct and with modern technologies the chances of osmosis is pretty slim. However, I do know for fact that surveyors are now stating in their survey “that it is recommended that a GRP hull boat is lifted and stored ashore for a period of around 4 months annually”.

At the end of the day, no matter what anyone says, gel coat is porous and water does get in, although modern SP system products mean the gel is “less porous” but I would still recommend the boat is out for at least a month. (Personal opinion not company)."

So you pays yer money, and you takes yer choice...
 
erm ,just minute "no matter what anyone says, gelcoat is porous" - i mean really? That seems like saying "no matter what anyone says, tupperware is porous" where the backup info on this? And if hard plasticky shiny shiny gelcoat is porous then the grp matty stuff behind must also be porous so why no puddles in the bilges? I think in some regards these surveyor types are hocus pocus quasi-technical polytechnic types with a penchant for form-filling and tendency to quote old wives tales, and therefore simpletons.

Mind you, i'm in an arsey mood cos going on hol tomorrow so i can afford to burn a few threads, ahem.
 
Umm, well it is. Epoxy resins aren't porous, polyester resins are. They're not very porous, otherwise it would be like trying to make a sieve float, but they do let tiny amounts of moisture through. You could have a boat built using epoxy, of course, but it's four times the cost of polyester resins.

Anyway, we know it's porous, cos that's what causes osmosis. The resins are all two-part (otherwise they'd go solid in the tin, which is Not Very Helpful), and unused hardener (iirc) reacts with water to form something unpleasant. So if you sort of guessed at the proportions (like they used to), and didn't stir it properly, then you'd get little pockets of unused hardener in the gel. When the moisture gets in through the porous gelcoat, it reacts with the hardener and gives off gas, which forms osmotic blisters.

Anyway, I do have puddles in the bilges, but that may be from the sternglands. As for suveyors, a bit like boating journos, I suspect you could blag it, as long as you had indemnity insurance that said your opinions didn't count, and you couldn't even be sure if it was a boat. Just need a hammer, clipboard and a little paintscraper to [no thanks] the antifouling with.

Speaking of which, how would a surveyor have dealt with your copper sheet stuff?
 
It\'s not the gelcoat!

I must dissagree with your understanding of osmosis. It is indeed osmotic pressure forcing water into uncured resins. However, they are in the glass fibre layup, where there are pockets between glass strands, of uncured or partially cured resins. The gelcoat is made of fillers and resin, so they are no pockets of uncured resin, but of course is semi-porous. The reason for blisters, is that the first layer of the glass layup, is the first to be affected, thus putting undue pressure on the gecloat, thus causing the blister. In the bad old days, in the 70's, where quality control and resin technology was in it's infancy, it was the middle of the layup which got affected, resulting in total delamination. If, as you suggest it is just the gelcoat, then there is no other problem than one of cosmetics. As I understand, boats have actually sunk due to severe osmosis.
If a barrier layer of say, epoxy resin, is put between the gelcoat and the glass layup, then this solves the problem.
Personally, I think modern boats can be left in the water for several seasons, with just a short time out for the usual cleaning & a/foul
 
we had the world and his wife round as we were putting the stuff on in antibes - incl a surveyor. He seemed over the moon bout it, saying how normal eroding antifoul is full of poison and so on, whereas this copper was ecologically sound and last for ages, ahem. As it happens, not that sound i spose since i proceeded to sprinkle the stuff all along the coast between there and the uk...

theoretically, there was a piece of metal skinning the whole boat so i spose it was better.

so, next time mjf takes his boat out he cd just take it to bare hull, wham on some epoxy, then some antifould and that's that? I am *certain that he will be okay over winter tho.




*This mite be complete bullshit, but the boat isn't gonna dissolve is it. No. Well, i don't think it is. And big boats spend years and years in the water.
 
All laminates in a marine environment will allow water to pass through them (in vapour form) and are thus susceptible to osmosis.

Any gelcoat epoxy/vinyl ester/polyester is a semi permiable membrane, some let less through than others.

I'll search for some evidence, (I have some somewhere I'm sure) as someone will no doubt question these remarks?
 
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